International Potato Center: World Sweetpotato Atlas

Global Sweetpotato Cultivation

In 2000, CIP published A Global Geo-Referenced Database of Sweetpotato Distribution, by Luisa Huaccho and Robert J. Hijmans, based on data from the United Nations Food and Agriculture Organization (FAO) and other sources. From 2000 to 2006, global sweetpotato cultivation declined slightly in both area of cultivation and average yields, but FAO production data for 2007 indicate some rebounding.

The vast majority of sweetpotato production remains in eastern Asia, according to FAO approximately 80 percent of the global crop being produced in China. However, in China and other countries of eastern Asia such as Viet Nam, the role of sweetpotato is changing from that of a staple crop to a source of feed for animals (primarily pigs) and raw material for industrial production.

Sweetpotato provides an essential food source with very high production per capita across the relatively humid areas of Africa, from the coastal west to the central and southern areas of the continent. There is evidence of rapidly increasing sweetpotato production in some countries of Africa, but ironically it is in Africa, where the crop's local importance can be very high, that production data are the most tentative.

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This map portrays sweetpotato cultivation by area and estimated yields by nation and sub-nationally as appropriate and where data are available. Yields of sweetpotato per unit of land vary widely, from over twenty-five tons per hectare in high-input agricultural systems to below three tons per hectare where sweetpotato is grown as a subsistence crop with minimal use of fertilizers or other inputs, as in most of Africa.

The primary source of sweetpotato cropping data at the national level is FAO, with a few exceptions and revisions noted below. Where a consistent trend in either area cultivated or national average yields is apparent from 2005 through 2007, or if no change is reported across those three years, values for 2007 are utilized. Where fluctuation has been reported for either area cultivated or yields, a weighted average of the three years (greatest weight to 2007, least to 2005) is utilized.

Data quality is a challenging issue for sweetpotato, especially in Africa, for several reasons:

Sweetpotato is often cultivated in mixed stands with other crops on small plots of land;

In many areas, sweetpotato can be grown throughout the calendar year, so that production cannot be ascertained during a well-defined harvest;

In many countries, sweetpotato is not marketed in large quantities, and is often consumed close to the point of harvest.

Mozambique provides an example of this challenge. FAO data since 2000 report total land under cultivation at 9,000 hectares, while a survey undertaken in April of 2004 estimated 96,000 hectares, over ten times the figure reported by FAO. (Please refer to the Mozambique chapter.) The higher estimate, used for the map, seems consistent with the general pattern of the region, but in truth nobody knows with precision or certainty the extent of the crop in Mozambique or in many other countries of Africa.

Countries where no data are reported by FAO or other sources currently known to CIP, but where sweetpotato cultivation likely does occur, are shaded darker gray. Those include, in Africa: Central African Republic, Guinea Bissau, and The Gambia. In South America, no sweetpotato data are reported by FAO or other known sources for Colombia.

Countries where data quality seems especially tentative, generally where reported production data are likely below actual levels, are shaded lighter gray. This assessment is based on three factors:

Production is not reported in areas where climatic and physical conditions are suitable for sweetpotato, and available literature indication that some production does occur;

Reported production data reveal strong discrepancies across national borders not attributable to significant differences in physical or other known factors;

Production per capita is extremely low, especially if those values are significantly below values reported by adjacent countries.

Countries in the light gray zone are all in Africa, from west to east: Sierra Leone, Liberia, Cote d'Ivoire, Ghana, Togo, Benin, Congo Republic, Congo DRC, Gabon, and Zimbabwe.

Two other countries are partially in the light gray zone, Sudan and Angola. Sudan's reported area of less than 1,000 hectares is far below potential for the humid south, and two provinces of Angola were omitted from a report noted below.

Notes on particular countries: Countries in orange are among those included in the World Sweetpotato Atlas. Please consult the respective chapters for more details.

Africa

Angola: Sub-national (provincial) distribution and yield estimates are consistent with a 2003 report by the FAO and World Food Programme, but overall cultivation has been adjusted to most recent data reported by FAO, indicating much higher production than reported in 2003.

Madagscar: National cultivation is consistent with FAO data, but two yield values can be seen, consistent with literature indicating extensive but lower yielding sweetpotato cultivation at the southern extreme of the island.

Malawi: Production data is reported by the Famine Early Warning (FEWSNET) for 2006, since FAO apparently reports all root and tuber crops in Malawi as "potato." However, yield values at 14.5 tons per hectare are oddly much higher than yields reported from surrounding countries.

Mozambique: The study conducted in 2004 remains the most comprehensive data currently available, indicating areas under cultivation over ten times that reported by FAO.

Nigeria: Total production data by state were provided via personal communication of Malachy Akoroda. Yields are indicated at the national level estimate, 3.4 tons per hectare, as reported by FAO, and area cultivated was derived from these two values. This production estimate is lower than the national estimate reported by FAO. Relative distribution is consistent with available literature, but should still be considered tentative.

Uganda: Total production is consistent with FAO reporting. Sub-national distribution is consistent with Government of Uganda reports by province.

Zambia:Data are reported by the Central Statistics Office of the Government of Zambia (2003/2004), much higher than reported by FAO.

Asia - Pacific

China: Government data obtained via the CIP regional office have been utilized, but by necessity generalized. The names of many administrative units cannot be reconciled, and data values of adjacent small areas are sometimes impossibly variant. All production data have been totaled by province, but the distribution of cultivation within provinces has been estimated consistent with available literature.

Papua New Guinea: The distribution of sweetpotato has not been carefully documented in spite of the enormous importance of the crop, much of it used to feed pigs. Since it is widely grown, no attempt has been made here to estimate relative sub-national distribution.

Viet Nam: Relative distribution and yield values are consistent with Government of Viet Nam reports cited in the chapter, but those data have been adjusted to current FAO reports.